The torques that will act as a load on doing the measuring of rheological zroerrties are normally very small, such as 10.sup.-7 to 10.sup.-2 Nm. The drive shaft of the rheometer is normally journalled in precision air bearings so as to provide such low torques. Other external torques of friction that will load the shaft therefore cannot be accepted. If there is a wish to perform the rheological measuring of the sample put under pressure the sample must be maintained under pressure, while at the same time a rotating movement is transferred to the sample. If the shaft is sealed with a box or other types of friction generating seals there will be a load from the frictional torque that is not desired.
It is previously known to enclose the sample in a closed measuring cell and to transfer a rotating movement without physical contact from a driving motor that constitutes the rheometer to the sample by means of magnets. In such an embodiment at least two major drawbacks will arise. Firstly, the closed measure cell will be classified as a pressure vessel for which specific safety regulations will apply. Secondly, the clutch or connection made of magnets will constitute an elastic connection which as a result of e.g. a slip will render dynamic measurings, e.g. such as oscillating movements of the driving motor, difficult or even impossible